ATMOSPHERIC HEAT BUDGET

Only 50% of insolation is actually absorbed by the Earth, then re-radiated back into the atmosphere.

Of the other 50%:

1) 25% reflected back into space by the air and clouds. (scattering = when air particles in the atmosphere reflect UV radiation). Cirrus clouds reflect 30-40% of UV radiation, Cumulonimbus clouds reflect 90% and snow and ice reflect 95%.